Generally, infant seats (such as an infant seat installed on a shopping cart, and a stroller) provided in public places, such as a supermarket, have a support means for preventing an infant from falling from the infant seats. Generally, such a support means has a grab bar which extends at least along a forward end of the infant seat. With respect to such infant seats, reference can be made to, for example, Unexamined Japanese Patent Application Laid-Open Specification Nos. Hei 10-211880 and 9-30421. However, in many cases, such infant seats have a problem in that the infant seats are unsanitary. Specifically, when an infant is seated in the infant seat, the infant bites and licks the above-mentioned grab bar and the like, so that the seat becomes unsanitary. Further, generally, such infant seats provided in public places are repeatedly used without being washed and, hence, an infant in the infant seat is exposed to dirt and germs which adhere to the infant seat.
For solving the above-mentioned problems, various proposals have been made. For example, U.S. Pat. No. 5,829,835 discloses a convertible combination of shopping cart seat liner and diaper bag for use as both a seat liner and a diaper bag (hereinafter, frequently referred to simply as “seat liner/diaper bag”), the convertible combination comprising: a flexible, upstanding container for accommodating therein an infant, which has two leg openings; a seat liner and diaper bag converting means; and a handle for enabling a user to readily carry the flexible, upstanding container when configured as the diaper bag. When the seat liner/diaper bag is used as a seat liner, the flexible, upstanding container prevents an infant seated in an infant seat from directly contacting the infant seat. Further, this patent document describes a pad which is used for covering the leg openings (hereinafter, referred to as “leg openings-covering pad”) when the above-mentioned seat liner/diaper bag is used as a diaper bag. However, this patent document describes only one specific example of such a leg openings-covering pad, which is shown in the drawings of this patent document. In such only one specific example, a lower portion of the leg openings-covering pad is fixedly attached to an inner wall of the above-mentioned container at a portion thereof which is just below the leg openings, and an upper portion of the leg openings-covering pad is detachably attached to an inner wall of the container at a portion thereof which is just above the leg openings. The upper portion of the leg openings-covering pad is attached to the inner wall of the container by a fastening means (such as a hook and loop fastener) and, when the seat liner/diaper bag is used as a shopping car seat liner, the leg openings are uncovered by detaching the upper portion of the leg openings-covering pad. However, when the leg openings are uncovered and an infant is seated on the seat liner, the infant is caused to be seated on the fastening means, such as a hook and loop fastener, so that there is a danger that the infant seated on the fastening means feels uncomfortable or even suffers scratches. Further, even when an upper portion of the leg openings-covering pad is fixedly attached to an inner wall of the above-mentioned container at a portion thereof which is just above the leg openings, and a lower portion of the leg openings-covering pad is detachably attached to an inner wall of the container at a portion thereof which is just below the leg openings, a problem also arises in that the fastening means is caused to contact the legs of an infant seated on the seat liner. Furthermore, even when the leg openings-covering pad is attached to an outer surface of the container, problems arise in that, when the seat liner/diaper bag is used as a diaper bag, the contents of the container are likely to push the leg openings-covering pad to thereby uncover the leg openings. For avoiding this problem, it becomes necessary to use a disadvantageously complicated fastening means or a disadvantageously complicated fastening method. Further, generally, it is unlikely that a bag is used exclusively for carrying only diapers and it is of course desirable that a bag can also contain other articles than diapers. However, especially when the above-mentioned leg openings-covering pad is attached to the outer surface of the container of the seat liner/diaper bag of this patent document, the leg openings-covering pad is likely to be partially or entirely detached from the container by the deformation of the container when relatively heavy articles are accommodated in the container. For avoiding this problem, it becomes necessary to use a disadvantageously complicated fastening means or a disadvantageously complicated fastening method.
Further, U.S. Pat. No. 7,100,982 discloses a shopping cart seat cover which can be removably placed inside the extendable platform of a shopping cart for seating one or two children, which has a substantially planar padded material having a peripheral edge, which when placed inside the extendable platform, forms a seat capable of seating one or two children. The above-mentioned seat formed by the seat cover comprises a front side, a back side, a bottom side, a right side and a left side, and only the peripheral edge of the front side and the peripheral edge of the back side comprise elastic means. When the shopping cart seat cover of this patent document is placed on the above-mentioned extendable platform of a shopping cart, the elastic front and rear sides of the peripheral edge of the planar padded material are bent so that the planar padded material is formed into a seat capable of seating one or two infants thereon. In the shopping cart seat cover of this patent document, the extendable platform is fully covered by the peripheral edge of the planar padded material. Further, the above-mentioned planar padded material has two apertures for allowing the legs of one or two children to extend out from the seat, and is provided with a flap(s) capable of closing the apertures. In this patent document, the flap(s) is attached to the above-mentioned front side of the peripheral edge in substantially the same manner as in the above-mentioned U.S. Pat. No. 5,829,835. Therefore, U.S. Pat. No. 7,100,982 has the same problems as mentioned above in connection with U.S. Pat. No. 5,829,835. Furthermore, the shopping cart seat cover of this patent document has attached thereto a container for accommodating therein the planar padded material in a folded configuration. This patent document states that the shopping cart seat cover of this patent document has improved the comfort and safety of the infant(s) seated in the infant seat. However, as apparent from the structure of the shopping cart seat cover as shown in the drawings of this patent document, the shopping cart seat cover is not completely accommodated in the extendable platform of a shopping cart, but is placed on top of the extendable platform. Therefore, the shopping cart seat cover of this patent document has a problem in that it is difficult to provide a support having a height sufficient for preventing an infant from falling from the seat. If it is attempted to provide the shopping cart seat cover of this patent document with a support wall or the like, which has a sufficient height for preventing the infant from falling from the seat, the portability of the shopping cart seat cover becomes disadvantageously poor. Further, the infant seats provided on shopping carts have various sizes and various designs. However, since the shopping cart seat cover of this patent document comprises a substantially planar padded material, it is very difficult to select such an appropriate material for the planar padded material and such an appropriate design that the shopping cart seat cover of this patent document can be fittedly, stably and safely installed on top of the extendable platforms of shopping carts of various sizes and designs. In addition, when the above-mentioned shopping cart seat cover is carried, the above-mentioned planar padded material needs to be folded and accommodated in the above-mentioned container. That is, in the production of the shopping cart seat cover, it is necessary to choose such a material and a design as would be appropriate for installation on top of infant seats of various sizes and designs, and for carrying in a folded form; however, the appropriate choice of such a material and a design is very difficult. Therefore, the shopping cart seat cover of this patent document is not practical.